Projector

ABSTRACT

A projector includes first and second cooling targets and a cooling device. The cooling device includes a first compressor, a condenser, a first expander, a first evaporator configured to change the working fluid into a working fluid in a gas phase by using heat of the first cooling target, a heat exchanger including a first flow path through which the working fluid from the first expander flows and a second flow path, a second expander configured to decompress the working fluid from the first flow path, a second evaporator configured to change the working fluid flowing into the second flow path into the working fluid in a gas phase by using heat of the second cooling target, and a second compressor. The heat exchanger cools the working fluid flowing through the first flow path by the working fluid flowing through the second flow path.

The present application is based on, and claims priority from JPApplication Serial Number 2020-012782, filed Jan. 29, 2020, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a projector.

2. Related Art

JP-A-2015-132659 discloses a projector including an indoor unit that isprovided indoors and projects an image and an outdoor unit that isprovided outdoors.

In the projector disclosed in JP-A-2015-132659, the indoor unit includesR, G, B laser heat sinks, a first refrigerant pipe, a drain pipe, and anelectronic expansion valve, in addition to R, G, B laser clusters, anoptical combining unit, and a projection lens. The outdoor unit includesa second refrigerant pipe, a cooling device, and a refrigerant heater. Acommunication line and a refrigerant pipe that couples an end of thefirst refrigerant pipe and an end of the second refrigerant pipe andcouples the other end of the first refrigerant pipe and the other end ofthe second refrigerant pipe are arranged between the indoor unit and theoutdoor unit.

In the projector, the electronic expansion valve, the G laser heat sink,the B laser heat sink, and the R laser heat sink are coupled in seriesin this order via the first refrigerant pipe.

The second refrigerant pipe forms a loop refrigerant path together withthe first refrigerant pipe via the refrigerant pipe. The refrigerantflows in one end of the electronic expansion valve, the laser heatsinks, the refrigerant heater, a refrigerant compressor and a condenserof the cooling device, and the other end of the electronic expansionvalve in this order.

The refrigerant compressor compresses a refrigerant gas to increase atemperature and a pressure of the refrigerant gas to a high temperatureand a high pressure. The condenser exchanges heat between therefrigerant gas at a high temperature and a high pressure and outsideair that is blown into the outdoor unit from outside by a fan, therebyconverting the refrigerant gas into a high-pressure liquid refrigerant.

The electronic expansion valve decompresses the high-pressure liquidrefrigerant into a liquid refrigerant that is easy to be vaporized. Theelectronic expansion valve controls a decompressing amount of arefrigerant in the first refrigerant pipe to control an evaporationtemperature of the refrigerant, and cools the laser heat sinks by alatent heat effect of the refrigerant.

When the refrigerant flows into the refrigerant compressor in a state ofbeing not completely vaporized, the refrigerant compressor is adverselyaffected. Thus, the refrigerant flowing into the refrigerant compressoris heated by the refrigerant heater.

According to the configuration as described above, in portions of therefrigerant path from the one end of the electronic expansion valve tothe laser heat sinks and the refrigerant heater, the laser heat sinksand the like are maintained at a constant temperature by the latent heateffect of the refrigerant. In this manner, the cooling device can coolthe laser heat sinks and the R, G, B laser clusters to certain constanttemperatures by the refrigerant circulating in the refrigerant path.

However, since the projector disclosed in JP-A-2015-132659 includes theoutdoor unit coupled to the indoor unit via the refrigerant pipe and thecommunication line, there is a problem that installation of theprojector is complicated.

SUMMARY

projector according to an aspect of the present disclosure modulates andprojects light emitted from a light source. The projector includes afirst cooling target, a second cooling target, a cooling deviceconfigured to cool the first cooling target and the second coolingtarget, and an exterior housing accommodating the first cooling target,the second cooling target, and the cooling device. The cooling deviceincludes a first pipe, a second pipe, a third pipe, a fourth pipe, afifth pipe, a sixth pipe, a seventh pipe, a first compressor configuredto compress a working fluid in a gas phase, a condenser coupled with thefirst compressor via the first pipe, and configured to condense theworking fluid in a gas phase compressed by the first compressor into aworking fluid in a liquid phase, a first expander coupled with thecondenser via the second pipe, and configured to decompress the workingfluid in a liquid phase condensed by the condenser to change the workingfluid in a liquid phase into a working fluid in a mixed phase of aliquid phase and a gas phase, a first evaporator coupled with the firstexpander via the third pipe, configured to change a part of the workingfluid flowing from the first expander into the working fluid in a gasphase by using heat transferred from the first cooling target, andconfigured to discharge the working fluid changed into a gas phase tothe first compressor coupled with the first evaporator via the fourthpipe, a heat exchanger coupled with the first expander via the thirdpipe, and including a first flow path through which the other part ofthe working fluid flowing from the first expander flows and a secondflow path different from the first flow path, a second expander coupledwith the heat exchanger via the fifth pipe, configured to decompress theworking fluid in a liquid phase flowing from the first flow path tochange the working fluid in a liquid phase into the working fluid in amixed phase of a liquid phase and a gas phase, and configured todischarge the working fluid in a mixed phase of a liquid phase and a gasphase to the second flow path of the heat exchanger via the sixth pipe,a second evaporator configured to change, into the working fluid in agas phase, the working fluid in a liquid phase flowing into the secondflow path from the second expander by using heat transferred from thesecond cooling target, and a second compressor coupled with the firstcompressor via the fourth pipe, and coupled with the second evaporatorvia the seventh pipe, the second compressor being configured to compressthe working fluid in a gas phase flowing from the second evaporator. Theheat exchanger is configured to cool the working fluid flowing from thefirst expander into the first flow path by the working fluid flowingfrom the second expander into the second flow path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an appearance of a projectoraccording to a first embodiment.

FIG. 2 is a schematic diagram showing an internal configuration of theprojector according to the first embodiment.

FIG. 3 is a schematic diagram showing a configuration of a light sourcedevice according to the first embodiment.

FIG. 4 is a schematic diagram showing a configuration of a coolingdevice according to the first embodiment.

FIG. 5 is a cross-sectional view schematically showing a configurationof a second evaporator according to the first embodiment.

FIG. 6 is a schematic diagram showing a configuration of a coolingdevice provided in a projector according to a second embodiment.

FIG. 7 is a cross-sectional view schematically showing a configurationof a heat exchanger according to the second embodiment.

FIG. 8 is a cross-sectional view schematically showing a modification ofthe heat exchanger according to the second embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment

Hereinafter, a first embodiment of the present disclosure will bedescribed with reference to drawings.

Schematic Configuration of Projector

FIG. 1 is a perspective view showing an appearance of a projector 1Aaccording to the present embodiment.

The projector 1A according to the present embodiment is an image displaydevice that modulates light emitted from a light source to form an imageaccording to image information, and enlarges and projects the formedimage on a projection surface such as a screen. As shown in FIG. 1, theprojector 1A includes an exterior housing 2 constituting an exterior ofthe projector 1A.

Configuration of Exterior Housing

The exterior housing 2 has a top surface portion 21, a bottom surfaceportion 22, a front surface portion 23, a rear surface portion 24, aleft side surface portion 25, and a right side surface portion 26. Theexterior housing 2 is formed into a substantially rectangularparallelepiped shape.

The bottom surface portion 22 has a plurality of leg portions 221 incontact with an installation surface on which the projector 1A ismounted.

The front surface portion 23 is positioned at an image projection sideof the exterior housing 2. The front surface portion 23 has an opening231 from which a part of a projection optical device 36 to be describedlater is exposed, and an image projected by the projection opticaldevice 36 passes through the opening 231. The front surface portion 23has an exhaust port 232 through which a cooling gas that cools a coolingtarget in the projector 1A is discharged to an outside of the exteriorhousing 2.

The right side surface portion 26 has an introduction port 261 throughwhich a gas such as air outside the exterior housing 2 is introducedinto the exterior housing 2 as a cooling gas.

Internal Configuration of Projector

FIG. 2 is a schematic diagram showing an internal configuration of theprojector 1A.

As shown in FIG. 2, the projector 1A further includes an imageprojection device 3 that is accommodated in the exterior housing 2.Although not shown in FIG. 2, the projector 1A includes a coolingtarget, a cooling device 5A (see FIG. 4) that cools the cooling target,a control device that controls an operation of the projector 1A, and apower supply device that supplies power to electronic components of theprojector 1A.

Configuration of Image Projection Device

The image projection device 3 forms an image according to imageinformation received from the control device, and projects the formedimage. The image projection device 3 includes a light source device 4, ahomogenizing unit 31, a color separation unit 32, a relay unit 33, animage forming unit 34, an optical component housing 35, and theprojection optical device 36.

The light source device 4 emits illumination light. A configuration ofthe light source device 4 will be described later in detail.

The homogenizing unit 31 homogenizes the illumination light emitted fromthe light source device 4. The homogenized illumination light passesthrough the color separation unit 32 and the relay unit 33 andilluminates a modulation area of a to-be-described light modulator 343of the image forming unit 34. The homogenizing unit 31 includes two lensarrays 311 and 312, a polarization conversion element 313, and asuperimposition lens 314.

The color separation unit 32 separates light incident from thehomogenizing unit 31 into a red light beam, a green light beam, and ablue light beam. The color separation unit 32 includes two dichroicmirrors 321 and 322, and a reflection mirror 323 that reflects the bluelight beam separated by the dichroic mirror 321.

The relay unit 33 is provided on an optical path of the red light beamthat has a longer optical path than other color light beams, andprevents a loss of the red light beam. The relay unit 33 includes anincident side lens 331, a relay lens 333, and reflection mirrors 332 and334. In the present embodiment, the relay unit 33 is provided on theoptical path of the red light beam. However, the present disclosure isnot limited thereto, and may have a configuration in which, for example,a blue light beam has a longer optical path than other color lightbeams, and the relay unit 33 is provided on an optical path of the bluelight beam.

The image forming unit 34 modulates an incident red light beam, greenlight beam, and blue light beam and combines the modulated color lightbeams to form an image. The image forming unit 34 includes,corresponding to the incident color light beams, three field lenses 341,three incident side polarizers 342, three light modulators 343, threeviewing angle compensation plates 344, three emission side polarizers345, and one color combining unit 346.

The light modulator 343 modulates light emitted from the light sourcedevice 4 according to image information. The light modulator 343includes a red light modulator 343R, a green light modulator 343G, and ablue light modulator 343B. In the present embodiment, the lightmodulator 343 is implemented by a transmissive liquid crystal panel, anda liquid crystal light valve includes the incident side polarizer 342,the light modulator 343, and the emission side polarizer 345.

The color combining unit 346 combines color light beams modulated by thelight modulators 343B, 343G, and 343R to form an image. Although thecolor combining unit 346 is implemented by a cross dichroic prism in thepresent embodiment, the present disclosure is not limited thereto. Forexample, the color combining unit 346 may be implemented by a pluralityof dichroic mirrors.

The optical component housing 35 accommodates the above-described units31 to 34 therein. An illumination optical axis Ax which is an opticalaxis in design is set in the image projection device 3. The opticalcomponent housing 35 accommodates the units 31 to 34 at predeterminedpositions on the illumination optical axis Ax. The light source device 4and the projection optical device 36 are provided at predeterminedpositions on the illumination optical axis Ax.

As will be described in detail later, the projector 1A includes a sealedhousing SC (see FIG. 4) of which a part is formed by the opticalcomponent housing 35. The sealed housing SC accommodates the incidentside polarizers 342, the light modulators 343, the viewing anglecompensation plates 344, the emission side polarizers 345, and the colorcombining unit 346 that constitute the image forming unit 34. Theincident side polarizers 342, the light modulators 343, the viewingangle compensation plates 344, the emission side polarizers 345, and thecolor combining unit 346 are cooled by a cooling gas circulating in thesealed housing SC. The cooling gas in the sealed housing SC is cooled bya second evaporator 55 (see FIG. 4) provided in the sealed housing SCamong constituent elements of the cooling device 5A.

The projection optical device 36 is a projection lens that enlarges andprojects an image incident from the image forming unit 34 onto aprojection surface. That is, the projection optical device 36 projectslight beams modulated by the light modulators 343B, 343G, and 343R. Theprojection optical device 36 is implemented as, for example, anassembled lens in which a plurality of lenses are accommodated in acylindrical lens barrel.

Configuration of Light Source Device

FIG. 3 is a schematic diagram showing a configuration of the lightsource device 4.

The light source device 4 emits illumination light to the homogenizingunit 31. As shown in FIG. 3, the light source device 4 includes a lightsource housing CA, a light source unit 41, an afocal optical element 42,a homogenizer optical element 43, a polarization separation element 44,a first light collecting element 45, a wavelength conversion element 46,a first phase difference element 47, a second light collecting element48, a diffusion reflection unit 49, and a second phase differenceelement RP that are accommodated in the light source housing CA.

The light source housing CA is implemented as a sealed housing intowhich dust or the like is less likely to enter.

The light source unit 41, the afocal optical element 42, the homogenizeroptical element 43, the polarization separation element 44, the firstphase difference element 47, the second light collecting element 48, andthe diffusion reflection unit 49 are provided on an illumination opticalaxis Ax1 set in the light source device 4.

The wavelength conversion element 46, the first light collecting element45, the polarization separation element 44, and the second phasedifference element RP are provided on an illumination optical axis Ax2that is set in the light source device 4 and orthogonal to theillumination optical axis Ax1. The illumination optical axis Ax2coincides with the illumination optical axis Ax at a position of thelens array 311. In other words, the illumination optical axis Ax2 is seton an extension line of the illumination optical axis Ax.

Configuration of Light Source Unit

The light source unit 41 includes a light source 411 that emits lightand a collimator lens 415.

The light source 411 includes a plurality of first semiconductor lasers412, a plurality of second semiconductor lasers 413, and a supportmember 414.

The first semiconductor laser 412 emits an s-polarized blue light beamL1 s that is excitation light. The blue light beam L1 s is, for example,a laser beam having a peak wavelength of 440 nm. The blue light beam L1s emitted from the first semiconductor laser 412 is incident on thewavelength conversion element 46.

The second semiconductor laser 413 emits a p-polarized blue light beamL2 p. The blue light beam L2 p is, for example, a laser beam having apeak wavelength of 460 nm. The blue light beam L2 p emitted from thesecond semiconductor laser 413 is incident on the diffusion reflectionunit 49.

The support member 414 supports the plurality of first semiconductorlasers 412 and the plurality of second semiconductor lasers 413 arrangedin an array on a plane orthogonal to the illumination optical axis Ax1.The support member 414 is a metal member having heat conductivity, andis coupled with a first evaporator 54 to be described later via a heattransfer member TM. Then, heat of the light source 411 including thesemiconductor lasers 412 and 413 which are heat sources is transferredto the first evaporator 54 via the heat transfer member TM. As a result,the light source 411 is cooled.

The blue light beam L1 s emitted from the first semiconductor laser 412and the blue light beam L2 p emitted from the second semiconductor laser413 are converted into parallel light beams by the collimator lens 415,and are incident on the afocal optical element 42.

In the present embodiment, the light source 411 emits the s-polarizedblue light beam L1 s and the p-polarized blue light beam L2 p. However,the present disclosure is not limited thereto, and the light source 411may emit blue light beams that are linearly polarized light beams havingthe same polarization direction. In this case, a phase differenceelement that coverts one type of incident linearly polarized light beaminto light containing an s-polarized light beam and a p-polarized lightbeam may be provided between the light source unit 41 and thepolarization separation element 44.

Configuration of Afocal Optical Element And Homogenizer Optical Element

The afocal optical element 42 adjusts light beam diameters of the bluelight beams L1 s and L2 p incident from the light source unit 41, andcauses the blue light beams L1 s and L2 p to be incident on thehomogenizer optical element 43. The afocal optical element 42 includes alens 421 that collects incident light beams and a lens 422 thatcollimates the light beams collected by the lens 421.

The homogenizer optical element 43 homogenizes an illuminancedistribution of the blue light beams L1 s and L2 p. The homogenizeroptical element 43 includes a pair of multi-lens arrays 431 and 432.

Configuration of Polarization Separation Element

The blue light beams L1 s and L2 p that passed through the homogenizeroptical element 43 are incident on the polarization separation element44.

The polarization separation element 44 is a prism-type polarization beamsplitter, and separates an s-polarized component and a p-polarizedcomponent contained in the incident light beams. Specifically, thepolarization separation element 44 reflects the s-polarized componentand transmits the p-polarized component. The polarization separationelement 44 has a color separation characteristic that allows a lightbeam having a wavelength equal to or larger than a predeterminedwavelength to pass through regardless either the s-polarized componentor the p-polarized component. Therefore, the s-polarized blue light beamL1 s is reflected by the polarization separation element 44 and incidenton the first light collecting element 45. On the other hand, thep-polarized blue light beam L2 p passes through the polarizationseparation element 44 and is incident on the first phase differenceelement 47.

Configuration of First Light Collecting Element

The first light collecting element 45 collects the blue light beam L1 sreflected by the polarization separation element 44 to the wavelengthconversion element 46. The first light collecting element 45 collimatesfluorescence YL incident from the wavelength conversion element 46.Although the first light collecting element 45 includes two lenses 451and 452 in an example in FIG. 3, the number of lenses constituting thefirst light collecting element 45 is not limited.

Configuration of Wavelength Conversion Element

The wavelength conversion element 46 is excited by an incident lightbeam, generates the fluorescence YL having a longer wavelength than theincident light beam, and emits the fluorescence YL to the first lightcollecting element 45. In other words, the wavelength conversion element46 converts a wavelength of the incident light beam and emits theconverted light beam. The fluorescence YL generated by the wavelengthconversion element 46 is, for example, a light beam having a peakwavelength of 500 nm to 700 nm. The wavelength conversion element 46includes a wavelength conversion unit 461 and a heat dissipation unit462.

The wavelength conversion unit 461 includes a wavelength conversionlayer and a reflection layer (not shown). The wavelength conversionlayer includes a phosphor that diffuses and emits the fluorescence YLthat is a non-polarized light beam obtained by converting a wavelengthof the incident blue light beam L1 s. The reflection layer reflects thefluorescence YL incident from the wavelength conversion layer toward afirst light collecting element 45 side.

The heat dissipation unit 462 is provided on an opposite side of thewavelength conversion unit 461 from a light incident side, anddischarges heat generated by the wavelength conversion unit 461.

The fluorescence YL emitted from the wavelength conversion element 46passes through the first light collecting element 45 along theillumination optical axis Ax2, and then is incident on the polarizationseparation element 44 having the color separation characteristic. Then,the fluorescence YL passes through the polarization separation element44 along the illumination optical axis Ax2 and is incident on the secondphase difference element RP.

The wavelength conversion element 46 may be rotated around a rotationaxis parallel to the illumination optical axis Ax2 by a rotation devicesuch as a motor.

Configuration of First Phase Difference Element and Second LightCollecting Element

The first phase difference element 47 is provided between thepolarization separation element 44 and the second light collectingelement 48. The first phase difference element 47 converts the bluelight beam L2 p that passed through the polarization separation element44 into a circularly polarized blue light beam L2 c. The blue light beamL2 c is incident on the second light collecting element 48.

The second light collecting element 48 collects the blue light beam L2 cincident from the first phase difference element 47 to the diffusionreflection unit 49. The second light collecting element 48 collimatesthe blue light beam L2 c incident from the diffusion reflection unit 49.The number of lenses constituting the second light collecting element 48can be changed as appropriate.

Configuration of Diffusion Reflection Unit

The diffusion reflection unit 49 reflects and diffuses the incident bluelight beam L2 c at the same diffusion angle as the fluorescence YLemitted from the wavelength conversion element 46. An example of aconfiguration of the diffusion reflection unit 49 includes a reflectionplate that Lambert reflects the incident blue light beam L2 c and arotation device that rotates the reflection plate around a rotation axisparallel to the illumination optical axis Ax1.

The blue light beam L2 c reflected by the diffusion reflection unit 49passes through the second light collecting element 48, and then isincident on the first phase difference element 47. The blue light beamL2 c is converted into a circularly polarized light beam in a directionopposite to a rotation direction when the blue light beam L2 c isreflected by the diffusion ref lection unit 49. Therefore, the bluelight beam L2 c incident on the first phase difference element 47 viathe second light collecting element 48 is converted into the s-polarizedblue light beam L2 s instead of the p-polarized blue light beam L2 pincident on the first phase difference element 47 from the polarizationseparation element 44. Then, the blue light beam L2 s is reflected bythe polarization separation element 44 and is incident on the secondphase difference element RP. That is, light that is incident on thesecond phase difference element RP from the polarization separationelement 44 is white light in which the blue light beam L2 s and thefluorescence YL are mixed.

Configuration of Second Phase Difference Element

The second phase difference element RP converts the white light incidentfrom the polarization separation element 44 into light in which ans-polarized light beam and a p-polarized light beam are mixed. Whiteillumination light WL converted in this manner is incident on thehomogenizing unit 31.

Configuration of Cooling Device

FIG. 4 is a schematic diagram showing the cooling device 5A. In FIG. 4,a circulation direction of a working fluid is indicated by dotted linearrows, and a circulation direction of a cooling gas in the sealedhousing SC is indicated by shaded arrows.

The cooling device 5A cools a cooling target of the projector 1A.Specifically, the cooling device 5A circulates the working fluid whosephase is changed between a liquid phase and a gas phase to cool thecooling target. The cooling target includes a first cooling target CT1and a second cooling target CT2. As shown in FIG. 4, the cooling device5A, the first cooling target CT1, and the second cooling target CT2 areaccommodated in the exterior housing 2. A management temperature rangeof the first cooling target CT1 is defined as a first temperature range,and the first cooling target CT1 includes the light source 411 in thepresent embodiment. A management temperature range of the second coolingtarget CT2 is defined as a second temperature range lower than the firsttemperature range, and the second cooling target CT2 includes the lightmodulator 343 in the present embodiment. That is, the managementtemperature range of the second cooling target CT2 is lower than themanagement temperature range of the first cooling target CT1.

A lower limit value of the first temperature range may be lower than anupper limit value of the second temperature range. In this case, anintermediate value of the first temperature range may be higher than anintermediate value of the second temperature range.

The cooling device 5A includes a first compressor 51, a condenser 52, afirst expander 53, a first evaporator 54, the second evaporator 55, asecond expander 56, a second compressor 57, a pipe 58 that couples theseunits such that the working fluid can circulate therein, and a coolingfan 59.

Configuration of Pipe

The pipe 58 includes a first pipe 581, a second pipe 582, a third pipe583, a fourth pipe 584, a fifth pipe 585, a sixth pipe 586, and aseventh pipe 587.

The first pipe 581 couples the first compressor 51 and the condenser 52.The second pipe 582 couples the condenser 52 and the first expander 53.The third pipe 583 couples the first expander 53, the first evaporator54, and a first inflow portion 551 (see FIG. 5) of the second evaporator55. The fourth pipe 584 couples the first evaporator 54, the secondcompressor 57, and the first compressor 51. The fifth pipe 585 couples afirst outflow portion 553 (see FIG. 5) of the second evaporator 55 andthe second expander 56. The sixth pipe 586 couples the second expander56 and a second inflow portion 554 (see FIG. 5) of the second evaporator55. The seventh pipe 587 couples a second outflow portion 556 (see FIG.5) of the second evaporator 55 and the second compressor 57.

The third pipe 583 includes a flow dividing pipe 5831 and branch pipes5832 and 5833.

The flow dividing pipe 5831 couples the first expander 53 and the branchpipes 5832 and 5833. The flow dividing pipe 5831 is configured such thatthe working fluid flowing from the first expander 53 flows through aninside of the flow dividing pipe 5831, and branches toward the firstevaporator 54 and the second expander 56.

The branch pipe 5832 couples the flow dividing pipe 5831 and the firstevaporator 54. The branch pipe 5832 is configured such that a part ofthe working fluid branching at the flow dividing pipe 5831 flows to thefirst evaporator 54. The branch pipe 5832 corresponds to a first branchpipe.

The branch pipe 5833 couples the flow dividing pipe 5831 and the firstinflow portion 551 of the second evaporator 55. The branch pipe 5833 isconfigured such that the other part of the working fluid branching atthe flow dividing pipe 5831 flows to a first flow path 552 (see FIG. 5)of the second evaporator 55. The branch pipe 5833 corresponds to asecond branch pipe.

The third pipe 583 is configured such that a flow rate of the workingfluid flowing from the flow dividing pipe 5831 to the first evaporator54 via the branch pipe 5832 is larger than a flow rate of the workingfluid flowing from the flow dividing pipe 5831 to the second evaporator55 via the branch pipe 5833. However, the present disclosure is notlimited thereto. A flow rate of the working fluid flowing in the branchpipe 5832 and a flow rate of the working fluid flowing in the branchpipe 5833 may be the same, or a flow rate of the working fluid flowingin the branch pipe 5832 may be smaller than a flow rate of the workingfluid flowing in the branch pipe 5833.

The fourth pipe 584 includes branch pipes 5841 and 5842 and a joiningpipe 5843.

The branch pipe 5841 couples the first evaporator 54 and the joiningpipe 5843. The branch pipe 5841 is configured such that the workingfluid flowing from the first evaporator 54 flows to the joining pipe5843. The branch pipe 5841 corresponds to a third branch pipe.

The branch pipe 5842 couples the second compressor 57 and the joiningpipe 5843. The branch pipe 5842 is configured such that the workingfluid flowing from the second compressor 57 flows to the joining pipe5843. The branch pipe 5842 corresponds to a fourth branch pipe.

The joining pipe 5843 couples the branch pipes 5841 and 5842 and thefirst compressor 51. The working fluid flowing from the first evaporator54 via the branch pipe 5841 and the working fluid flowing from thesecond compressor 57 via the branch pipe 5842 join each other at thejoining pipe 5843, and flow to the first compressor 51.

Configuration of First Compressor

The first compressor 51 compresses the working fluid in a gas phase.That is, the first compressor 51 compresses the working fluid in a gasphase flowing from the fourth pipe 584 to increase a temperature and apressure of the working fluid in a gas phase to a high temperature and ahigh pressure. The working fluid in a gas phase whose temperature andpressure are increased by the first compressor 51 to a high temperatureand a high pressure flows to the condenser 52 via the first pipe 581.

Configuration of Condenser

The condenser 52 is coupled with the first compressor 51 via the firstpipe 581. The condenser 52 condenses the working fluid in a gas phasecompressed by the first compressor 51, that is, the high-temperature andhigh-pressure working fluid in a gas phase into a working fluid in aliquid phase. More specifically, the condenser 52 condenses the workingfluid in a gas phase into the high-pressure working fluid in a liquidphase by exchanging heat between the compressed working fluid in a gasphase with a cooling gas that is introduced from an outside of theexterior housing 2 to an inside of the exterior housing 2 and is blownto the condenser 52 by the cooling fan 59.

Configuration of First Expander

The first expander 53 is a decompressor, and is coupled with thecondenser 52 via the second pipe 582. The first expander 53 decompressesthe working fluid in a liquid phase condensed by the condenser 52, andchanges a state of the working fluid into a state in which a liquidphase and a gas phase are mixed. That is, the first expander 53 reducesa temperature of the working fluid. The first expander 53 is implementedby, for example, an expansion valve, specifically, an electronicexpansion valve, capable of controlling an evaporation temperature ofthe working fluid in a liquid phase.

Configuration of First Evaporator

The first evaporator 54 is coupled with the first expander 53 via thethird pipe 583. Specifically, the first evaporator 54 is coupled withthe first expander 53 via the flow dividing pipe 5831 and the branchpipe 5832. A part of the working fluid in the state in which a liquidphase and a gas phase are mixed flows into the first evaporator 54 fromthe first expander 53. That is, a part of the working fluid flows fromthe first expander 53 to the first evaporator 54.

As described above, the first evaporator 54 is coupled with the supportmember 414 of the light source 411 via the heat transfer member TM, andheat generated by the plurality of first semiconductor lasers 412 andthe plurality of second semiconductor lasers 413 is transferred to thefirst evaporator 54 via the support member 414 and the heat transfermember TM. That is, the first evaporator 54 is coupled with the lightsource 411 in a heat transferable manner, and heat of the light source411 is transferred to the first evaporator 54.

By using the heat transferred from the light source 411, the firstevaporator 54 evaporates the working fluid in a liquid phase which is apart of the working fluid flowing from the first expander 53 and changesthe working fluid in a liquid phase into a working fluid in a gas phase.Accordingly, heat of the plurality of first semiconductor lasers 412 andthe plurality of second semiconductor lasers 413 is consumed, and theplurality of first semiconductor lasers 412 and the plurality of secondsemiconductor lasers 413 are cooled.

The first evaporator 54 is coupled with the first compressor 51 via thebranch pipe 5841 and the joining pipe 5843 of the fourth pipe 584. Thefirst evaporator 54 discharges the working fluid changed into a gasphase to the first compressor 51 via the fourth pipe 584.

As described above, the cooling device 5A includes a first circulationpath CR1 in which the working fluid flows in the first compressor 51,the first pipe 581, the condenser 52, the second pipe 582, the firstexpander 53, the third pipe 583, the first evaporator 54, and the fourthpipe 584 in this order, and the working fluid flows into the firstcompressor 51 again. As described above, the first circulation path CR1cools the light source 411 included in the first cooling target CT1.

Configuration of Second Evaporator

The second evaporator 55 is provided in the sealed housing SC, iscoupled with the first expander 53 via the third pipe 583, is coupledwith the second expander 56 via the fifth pipe 585 and the sixth pipe586, and is coupled with the second compressor 57 via the seventh pipe587. As will be described in detail later, the second evaporator 55cools the second cooling target CT2 by the working fluid in a liquidphase flowing from the second expander 56. In addition, the secondevaporator 55 cools the working fluid in the state in which a liquidphase and a gas phase are mixed, that is, the other part of the workingfluid flowing from the first expander 53, by the working fluid in aliquid phase flowing from the second expander 56, and changes theworking fluid flowing from the first expander 53 into a working fluid ina liquid phase.

FIG. 5 is a schematic diagram showing an internal configuration of thesecond evaporator 55.

As shown in FIG. 5, the second evaporator 55 includes a heat exchanger558.

The heat exchanger 558 exchanges heat between the other part of theworking fluid flowing from the first expander 53 and the working fluidin a liquid phase flowing from the second expander 56 and between thecooling gas in the sealed housing SC and the working fluid in a liquidphase flowing from the second expander 56, and cools the other part ofthe working fluid flowing from the first expander 53 and the cooling gasin the sealed housing SC by the working fluid in a liquid phase flowingfrom the second expander 56.

As shown in FIG. 5, the second evaporator 55 includes the first inflowportion 551, the first flow path 552, the first outflow portion 553, thesecond inflow portion 554, a second flow path 555, the second outflowportion 556, a heat transfer portion 557, and the heat exchanger 558.

The first inflow portion 551 is coupled with the first expander 53 viathe flow dividing pipe 5831 and the branch pipe 5833 of the third pipe583, and the working fluid from the first expander 53 flows into thefirst inflow portion 551.

The first flow path 552 couples the first inflow portion 551 and thefirst outflow portion 553. The working fluid in the state in which aliquid phase and a gas phase are mixed from the first expander 53 flowsto the first flow path 552 via the first inflow portion 551.

The first outflow portion 553 is coupled with the second expander 56 viathe fifth pipe 585. The working fluid flowing through the first flowpath 552 flows out of the first outflow portion 553 and flows to thesecond expander 56 via the fifth pipe 585.

The second inflow portion 554 is coupled with the second expander 56 viathe sixth pipe 586, and the working fluid from the second expander 56flows into the second inflow portion 554.

The second flow path 555 couples the second inflow portion 554 and thesecond outflow portion 556. The working fluid in a liquid phase flowingfrom the second expander 56 flows to the second flow path 555 via thesecond inflow portion 554.

The second outflow portion 556 is coupled with the second compressor 57via the seventh pipe 587. The working fluid flowing through the secondflow path 555 flows out of the second outflow portion 556 and flows tothe second compressor 57 via the seventh pipe 587.

The first flow path 552 and the second flow path 555 are provided in theheat transfer portion 557. The heat transfer portion 557 is formed of aheat transfer material such as metal. The first flow path 552 and thesecond flow path 555 are coupled to each other in a heat transferablemanner by the heat transfer portion 557. The heat transfer portion 557exchanges heat between the working fluid flowing through the first flowpath 552 and the working fluid flowing through the second flow path 555and between the cooling gas in the sealed housing SC and the workingfluid flowing through the second flow path 555. Specifically, the heattransfer portion 557 transfers heat from the working fluid flowingthrough the first flow path 552 to the working fluid flowing through thesecond flow path 555.

In the present embodiment, the heat exchanger 558 is provided in thesecond evaporator 55. The heat exchanger 558 includes the first flowpath 552, the second flow path 555, and a part of the heat transferportion 557. That is, the heat exchanger 558 is coupled with the firstexpander 53 via the third pipe 583 and is coupled with the secondexpander 56 via the sixth pipe 586. The heat exchanger 558 includes thefirst flow path 552 through an inside of which the working fluid flowingfrom the first expander 53 flows and the second flow path 555 through aninside of which the working fluid flowing from the second expander 56flows.

As will be described in detail later, the heat exchanger 558 exchangesheat between the working fluid flowing from the first expander 53 andflowing through the first flow path 552 and the working fluid flowingfrom the second expander 56 and flowing through the second flow path 555by the part of the heat transfer portion 557, and cools the workingfluid flowing through the first flow path 552. The working fluid flowingthrough the first flow path 552 is changed from the working fluid in thestate in which a liquid phase and a gas phase are mixed to the workingfluid in a liquid phase by the heat exchanger 558.

When each of the first flow path 552 and the second flow path 555 isformed of a tubular member, the heat transfer portion 557 may be amember that couples the tubular member forming the first flow path 552and the tubular member forming the second flow path 555 in a heattransferable manner. On the other hand, each of the first flow path 552and the second flow path 555 may be a flow path formed in the heattransfer portion 557.

Configuration of Second Expander

As shown in FIG. 4, the second expander 56 is coupled with the heatexchanger 558 of the second evaporator 55 via the fifth pipe 585, and iscoupled with the heat exchanger 558 of the second evaporator via thesixth pipe 586. The second expander 56 decompresses the working fluid ina liquid phase that is the working fluid flowing from the first outflowportion 553 of the second evaporator 55 via the fifth pipe 585, therebyfurther reducing a temperature of the working fluid and changing theworking fluid in a liquid phase into a working fluid in a state in whicha liquid phase and a gas phase are mixed. Then, the second expander 56discharges the working fluid that is in the state in which a liquidphase and a gas phase are mixed and whose temperature is reduced to thesecond flow path 555 via the sixth pipe 586 and the second inflowportion 554 of the second evaporator 55. That is, the second expander 56is a decompressor similar to the first expander 53, and is implementedby, for example, an expansion valve, specifically, an electronicexpansion valve.

An opening degree of the expansion valve constituting the first expander53 and an opening degree of the expansion valve constituting the secondexpander 56 can be separately adjusted. In other words, a temperature ofthe working fluid flowing out of the first expander 53 and a temperatureof the working fluid flowing out of the second expander 56 can beseparately adjusted.

Function of Second Evaporator

The second evaporator 55 is provided in the sealed housing SC in whichthe second cooling target CT2 is provided. The second cooling target CT2includes the incident side polarizer 342, the light modulator 343, theviewing angle compensation plate 344, the emission side polarizer 345,and the color combining unit 346. For example, the second cooling targetCT2 may be at least one of the light modulator 343 and the emission sidepolarizer 345. That is, although the second cooling target CT2 includesat least the light modulator 343 in the present embodiment, the secondcooling target CT2 may include at least the emission side polarizer 345.In this manner, the projector 1A includes the sealed housing SC in whichthe second cooling target CT2 and the second evaporator 55 are provided.

The second evaporator 55 evaporates the working fluid in a liquid phaseflowing into the second flow path 555 from the second expander 56 byusing heat of the cooling gas that is inside the sealed housing SC andis received from at least one heat source of the second cooling targetCT2, that is, by using heat transferred from the second cooling targetCT2, so as to change the working fluid in a liquid phase into a workingfluid in a gas phase. Specifically, the second evaporator 55 evaporatesthe working fluid in a liquid phase flowing from the second expander 56and flowing through the second flow path 555 to change the working fluidin a liquid phase into the working fluid in a gas phase. That is, theworking fluid flowing into the second compressor 57 from the secondoutflow portion 556 of the second evaporator 55 via the seventh pipe 587is the working fluid in a gas phase. Accordingly, the second evaporator55 cools the cooling gas in the sealed housing SC. As described above,the heat exchange between the cooling gas in the sealed housing SC andthe working fluid flowing through the second flow path 555 is performedby the heat transfer portion 557 of the heat exchanger 558 in the secondevaporator 55.

The projector 1A includes a circulation fan CF that circulates, in thesealed housing SC, the cooling gas inside the sealed housing SC.Further, a partition wall SC1 is disposed in the sealed housing SC. Thecooling gas cooled by the second evaporator 55 is circulated, by thecirculation fan CF, in the sealed housing SC along an air circulationflow path formed by the partition wall SC1. Accordingly, configurationsof the image forming unit 34 inside the sealed housing SC such as thelight modulator 343 and the emission side polarizer 345 are cooled bythe cooling gas cooled by the second evaporator 55.

As described above, in the second evaporator 55, the heat exchanger 558cools the working fluid flowing from the first expander 53 and flowingthrough the first flow path 552 by the working fluid flowing from thesecond expander 56 and flowing through the second flow path 555.Specifically, in the second evaporator 55, the heat exchanger 558 coolsthe working fluid in the state in which a liquid phase and a gas phaseare mixed, that is, the working fluid flowing from the first expander 53and flowing through the first flow path 552, by the working fluid cooledby the second expander 56 and flowing from the second expander 56, andchanges a working fluid flowing from the first flow path 552 and beforeflowing to the second expander 56 via the fifth pipe 585 into theworking fluid in a liquid phase. Accordingly, the working fluid in aliquid phase instead of the working fluid in a mixed phase of a liquidphase and a gas phase can flow into the second expander 56. When thesecond expander 56 expands the working fluid, generation of abnormalnoises such as those generated when the second expander 56 expands theworking fluid in a state in which a liquid phase and a gas phase aremixed can be prevented.

As described above, the second evaporator 55 includes the heat exchanger558. In other words, the second evaporator 55 is formed by integratingan evaporator and a heat exchanger.

The first flow path 552 and the second flow path 555 are not limited toa linearly extending flow path. For example, the first flow path 552 maymeander from the first inflow portion 551 toward the first outflowportion 553. Similarly, the second flow path 555 may meander from thesecond inflow portion 554 toward the second outflow portion 556. Thatis, each of the first flow path 552 and the second flow path 555 mayhave a bent portion, a folded portion, or a return portion that changesa flowing direction of the working fluid.

Configuration of Second Compressor

The second compressor 57 is coupled with the second evaporator 55 viathe seventh pipe 587. The second compressor 57 is coupled with the firstcompressor 51 via the fourth pipe 584.

The second compressor 57 compresses the working fluid in a gas phaseflowing from the second evaporator 55 via the seventh pipe 587. That is,the second compressor 57 increases a temperature and a pressure of theworking fluid in a gas phase to a high temperature and a high pressure.The working fluid in a gas phase compressed by the second compressor 57flows through the branch pipe 5842 of the fourth pipe 584, joins theworking fluid in a gas phase flowing through the branch pipe 5841 at thejoining pipe 5843, and flows to the first compressor 51.

Here, the second compressor 57 compresses the working fluid in a gasphase flowing from the second evaporator 55 in order to make a pressureof the working fluid in a gas phase flowing into the branch pipe 5842 ofthe fourth pipe 584 from the second compressor 57 substantially the sameas a pressure of the working fluid in a gas phase flowing into thebranch pipe 5841 of the fourth pipe 584 from the first evaporator 54.That is, the pressure of the working fluid in a gas phase compressed bythe second compressor 57 is substantially the same as the pressure ofthe working fluid in a gas phase discharged from the first evaporator54. Thus, the working fluid in a gas phase flowing through the branchpipe 5842 from the second compressor 57 and the working fluid in a gasphase flowing through the branch pipe 5841 from the first evaporator 54can be joined by the joining pipe 5843 and can easily flow to the firstcompressor 51.

A drive frequency of the second compressor 57 and a drive frequency ofthe first compressor 51 are substantially the same. Accordingly, it ispossible to prevent an increase in noises generated in the respectivecompressors 51 and 57 at a timing when phases of the drive frequenciescoincide with each other. The drive frequency of the first compressor 51and the drive frequency of the second compressor 57 being substantiallythe same includes the drive frequencies being the same.

As described above, the cooling device 5A includes a second circulationpath CR2 in which the working fluid flows through the first compressor51, the first pipe 581, the condenser 52, the second pipe 582, the firstexpander 53, the third pipe 583, the second evaporator 55, the fifthpath 585, the second expander 56, the sixth pipe 586, the secondevaporator 55, the seventh pipe 587, the second compressor 57, and thefourth pipe 584 in this order, and the working fluid flows into thefirst compressor 51 again. The second circulation path CR2 and the firstcirculation path CR1 share a path from the joining pipe 5843 of thefourth pipe 584 to the flow dividing pipe 5831 of the third pipe 583. Asdescribed above, the second circulation path CR2 cools the lightmodulator 343 and the like included in the second cooling target CT2.

In the present embodiment, a heat generation amount of the first coolingtarget CT1 including the light source 411 is larger than a heatgeneration amount of the second cooling target CT2 including the lightmodulator 343. Therefore, the flow dividing pipe 5831 is set such that aflow rate of the working fluid in a liquid phase supplied to the firstevaporator 54 via the branch pipe 5832 is larger than a flow rate of theworking fluid in a liquid phase supplied to the second evaporator 55 viathe branch pipe 5833, the fifth pipe 585, the second expander 56, andthe sixth pipe 586. Accordingly, the first cooling target CT1 whose heatgeneration amount is larger than the heat generation amount of thesecond cooling target CT2 can be more suitably cooled. Therefore, atemperature of the first cooling target CT1 can be maintained at atemperature within the first temperature range and a temperature of thesecond cooling target CT2 can be maintained at a temperature within thesecond temperature range.

As described above, in the cooling device 5A according to the presentembodiment, the first evaporator 54 can take heat generated by theplurality of first semiconductor lasers 412 and the plurality of secondsemiconductor lasers 413 to cool the light source 411. In addition, inthe cooling device 5A, the second evaporator 55 can take heat of thecooling gas in the sealed housing SC to cool the cooling gas, and hencecool the image forming unit 34 including the light modulator 343.Therefore, the two cooling targets can be cooled.

Effects of First Embodiment

The projector 1A according to the present embodiment described above canachieve the following effects.

For example, the projector 1A modulates and projects light emitted fromthe light source 411. The projector 1A includes the first cooling targetCT1, the second cooling target CT2, the cooling device 5A that cools thefirst cooling target CT1 and the second cooling target CT2, and theexterior housing 2 that accommodates the first cooling target CT1, thesecond cooling target CT2, and the cooling device 5A. The cooling device5A includes the first pipe 581, the second pipe 582, the third pipe 583,the fourth pipe 584, the fifth pipe 585, the sixth pipe 586, the seventhpipe 587, the first compressor 51, the condenser 52, the first expander53, the first evaporator 54, the second evaporator 55 having a functionof a heat exchanger, the second expander 56, and the second compressor57.

The first compressor 51 compresses the working fluid in a gas phase.

The condenser 52 is coupled with the first compressor 51 via the firstpipe 581. The condenser 52 condenses the working fluid in a gas phasecompressed by the first compressor 51 into the working fluid in a liquidphase.

The first expander 53 is coupled with the condenser 52 via the secondpipe 582. The first expander 53 decompresses the working fluid in aliquid phase condensed by the condenser 52, and changes a state of theworking fluid to a state in which a liquid phase and a gas phase aremixed.

The first evaporator 54 is coupled with the first expander 53 via thethird pipe 583. The first evaporator 54 changes a part of the workingfluid flowing from the first expander 53 into the working fluid in a gasphase by using heat transferred from the first cooling target CT1. Thefirst evaporator 54 discharges the working fluid that was changed to theworking fluid in a gas phase to the first compressor 51 coupled with thefirst evaporator 54 via the fourth pipe 584.

The heat exchanger 558 is coupled with the first expander 53 via thethird pipe 583. The heat exchanger 558 includes the first flow path 552through an inside of which the other part of the working fluid flowingfrom the first expander 53 flows, and the second flow path 555 differentfrom the first flow path 552.

The second expander 56 is coupled with the heat exchanger 558 via thefifth pipe 585. The second expander 56 decompresses the working fluidflowing from the first flow path 552 and changes a state of the workingfluid to a state in which a liquid phase and a gas phase are mixed. Thesecond expander 56 discharges the changed working fluid to the secondflow path 555 of the heat exchanger 558 via the sixth pipe 586.

The second evaporator 55 changes the working fluid in a liquid phaseflowing into the second flow path 555 from the second expander 56 intothe working fluid in a gas phase by using heat transferred from thesecond cooling target CT2.

The second compressor 57 is coupled with the first compressor 51 via thefourth pipe 584, and is coupled with the second evaporator 55 via theseventh pipe 587. The second compressor 57 compresses the working fluidin a gas phase flowing from the second evaporator 55.

The heat exchanger 558 cools the working fluid flowing from the firstexpander 53 and flowing through the first flow path 552 by the workingfluid flowing from the second expander 56 and flowing through the secondflow path 555.

According to such a configuration, the first cooling target CT1 can becooled by the first circulation path CR1 in which the working fluidflows through the first compressor 51, the first pipe 581, the condenser52, the second pipe 582, the first expander 53, the third pipe 583, thefirst evaporator 54, and the fourth pipe 584, and the working fluidflows to the first compressor 51 again. The second cooling target CT2can be cooled by the second circulation path CR2 in which the workingfluid flows through the first compressor 51, the first pipe 581, thecondenser 52, the second pipe 582, the first expander 53, the third pipe583, the heat exchanger 558 of the second evaporator 55, the fifth pipe585, the second expander 56, the sixth pipe 586, the heat exchanger 558of the second evaporator 55, the seventh pipe 587, the second compressor57, and the fourth pipe 584, and the working fluid flows to the firstcompressor 51 again.

Accordingly, the first cooling target CT1 and the second cooling targetCT2 can be cooled by one cooling device 5A. Therefore, it is notnecessary to provide a circulation path in which the working fluidcirculates for each cooling target, and the first circulation path CR1that cools the first cooling target CT1 and the second circulation pathCR2 that cools the second cooling target CT2 can share the firstcompressor 51, the first pipe 581, the condenser 52, the second pipe582, and the first expander 53. Therefore, the projector 1A includingthe cooling device 5A can be reduced in size.

Further, the cooling device 5A is provided in the exterior housing 2together with the first cooling target CT1 and the second cooling targetCT2. According to this configuration, the projector 1A can be easilyinstalled and an appearance of the projector 1A can be improved comparedwith a case in which a part of the cooling device 5A is provided outsidethe exterior housing 2. Further, the projector 1A can be implemented ina small size, and the projector 1A can be implemented to be portable.

Here, in a case in which the working fluid flowing into the secondexpander 56 is the working fluid in the state in which a liquid phaseand a gas phase are mixed, abnormal noises may be generated when thesecond expander 56 expands the working fluid.

In contrast, in the heat exchanger 558, the working fluid flowingthrough the first flow path 552 and before flowing into the secondexpander 56 is cooled by the working fluid flowing from the secondexpander 56 and flowing through the second flow path 555, and theworking fluid flowing through the first flow path 552 and before flowinginto the second expander 56 is changed into the working fluid in aliquid phase. Accordingly, the working fluid in a liquid phase insteadof the working fluid in the state in which a liquid phase and a gasphase are mixed can flow into the second expander 56, and generation ofthe abnormal noises during expansion of the working fluid in the secondexpander 56 can be prevented. Therefore, noise reduction of the coolingdevice 5A and the projector 1A can be achieved.

The heat exchanger 558 is provided in the second evaporator 55.

According to such a configuration, it is not necessary to separatelyprovide the second evaporator and the heat exchanger. Therefore, aconfiguration of the cooling device 5A can be prevented from becomingcomplicated since an increase in the number of components of the coolingdevice 5A is prevented. In addition, manufacturing costs of the coolingdevice 5A and the projector 1A can be prevented from increasing.

The first flow path 552 and the second flow path 555 constituting theheat exchanger 558 are coupled to each other in a heat transferablemanner.

According to such a configuration, the working fluid flowing through thefirst flow path 552 can be cooled by the working fluid flowing throughthe second flow path 555. Therefore, the working fluid flowing throughthe first flow path 552 and flowing to the second expander 56 can beeasily changed into the working fluid in a liquid phase.

The heat exchanger 558 includes the heat transfer portion 557. The firstflow path 552 and the second flow path 555 are provided in the heattransfer portion 557. The heat transfer portion 557 transfers heat fromthe working fluid flowing through the first flow path 552 to the workingfluid flowing through the second flow path 555.

According to such a configuration, heat exchange between the workingfluid flowing through the first flow path 552 and the working fluidflowing through the second flow path 555 can be promoted compared with acase in which a gas such as air is present between the first flow path552 and the second flow path 555. Therefore, the working fluid flowingthrough the first flow path 552 and before flowing into the secondexpander 56 can be easily changed into the working fluid in a liquidphase.

Each of the first expander 53 and the second expander 56 is implementedby an expansion valve. An opening degree of the expansion valveconstituting the first expander 53 and an opening degree of theexpansion valve constituting the second expander 56 can be separatelyadjusted.

According to such a configuration, a temperature of the working fluidflowing out of the first expander 53 and a temperature of the workingfluid flowing out of the second expander 56 can be separately adjusted.Therefore, the temperature of the working fluid flowing out of the firstexpander 53 can be set to a temperature suitable for cooling the firstcooling target CT1, and the temperature of the working fluid flowing outof the second expander 56 can be set to a temperature suitable forcooling the second cooling target CT2.

Here, when a drive frequency of the first compressor 51 and a drivefrequency of the second compressor 57 are different, noises of the firstcompressor 51 and noises of the second compressor 57 overlap with eachother at timing when phases of the drive frequencies coincide with eachother, noises of the cooling device 5A increase. In this case, thenoises increase at a constant cycle, and a user is likely to feeldiscomfort. On the other hand, when a difference between the drivefrequency of the first compressor 51 and the drive frequency of thesecond compressor 57 is very large, a cycle in which phases coincidewith each other is very long and a discomfort feeling of the user is notmuch. However, when the difference between the drive frequency of thefirst compressor 51 and the drive frequency of the second compressor 57is very large, that is, when the drive frequency of the first compressor51 is greatly different from the drive frequency of the secondcompressor 57, the second compressor 57 cannot compress the workingfluid flowing from the second evaporator 55 in accordance with apressure of the working fluid flowing from the first evaporator 54 tothe first compressor 51.

In contrast, the drive frequency of the first compressor 51 and thedrive frequency of the second compressor 57 are substantially the same.According to this configuration, noises can be prevented from becominglarge at a constant cycle while compression performance of thecompressors can be ensured. Therefore, the user is less likely to feeldiscomfort.

The third pipe 583 includes the flow dividing pipe 5831, the branch pipe5832 serving as a first branch pipe, and the branch pipe 5833 serving asa second branch pipe. The flow dividing pipe 5831 divides the workingfluid flowing from the first expander 53. The branch pipe 5832 isconfigured such that a part of the working fluid branching at the flowdividing pipe 5831 flows to the first evaporator 54. The branch pipe5833 is configured such that the other part of the working fluidbranching at the flow dividing pipe 5831 flows to the heat exchanger558.

The fourth pipe 584 includes the branch pipe 5841 serving as a thirdbranch pipe, the branch pipe 5842 serving as a fourth branch pipe, andthe joining pipe 5843. The branch pipe 5841 is coupled with the firstevaporator 54. The branch pipe 5842 is coupled with the secondcompressor 57. The working fluid flowing from the first evaporator 54via the branch pipe 5841 and the working fluid flowing from the secondcompressor 57 via the branch pipe 5842 join each other at the joiningpipe 5843, and flows to the first compressor 51.

According to such a configuration, the working fluid can flow from thefirst expander 53 to the first evaporator 54 and the heat exchanger 558.The working fluid can efficiently flow from the first evaporator 54 andthe second compressor 57 to the first compressor 51.

A heat generation amount of the first cooling target CT1 is larger thana heat generation amount of the second cooling target CT2. A flow rateof the working fluid in a liquid phase supplied to the first evaporator54 is larger than a flow rate of the working fluid in a liquid phasesupplied to the heat exchanger 558.

According to such a configuration, more working fluid than the workingfluid flowing to the heat exchanger 558 can flow to the first evaporator54 that cools the first cooling target CT1 whose heat generation amountis larger than the heat generation amount of the second cooling targetCT2. Therefore, the working fluid at a flow rate suitable for coolingthe first cooling target CT1 can flow to the first evaporator 54, and atemperature of the first cooling target CT1 can be easily maintained ata management temperature.

A management temperature range of the second cooling target CT2 is lowerthan a management temperature range of the first cooling target CT1.

According to such a configuration, the working fluid that is to flowthrough the second flow path 555 of the second evaporator 55 flows fromthe condenser 52 to the first expander 53, the first flow path 552 ofthe heat exchanger 558, and the second expander 56. Therefore, atemperature of the working fluid that cools the second cooling targetCT2 and flows to the second flow path 555 of the second evaporator 55can be lower than a temperature of the working fluid that cools thefirst cooling target CT1 and flows to the first evaporator 54.Accordingly, working fluids having suitable temperatures for cooling thefirst cooling target CT1 and the second cooling target CT2 having amanagement temperature range lower than the management temperature rangeof the first cooling target CT1 can respectively flow to the firstevaporator 54 and the second evaporator 55. Therefore, the cooling ofthe first cooling target CT1 and the cooling of the second coolingtarget CT2 can be suitably performed.

A pressure of the working fluid in a gas phase compressed by the secondcompressor 57 is substantially the same as a pressure of the workingfluid in a gas phase discharged from the first evaporator 54.

According to such a configuration, the working fluid in a gas phasedischarged from the first evaporator 54 and the working fluid in a gasphase compressed by the second compressor 57 can be easily joined by thefourth pipe 584. Therefore, the working fluid in a gas phase dischargedfrom the first evaporator 54 and the working fluid in a gas phasedischarged from the second compressor 57 can easily and efficiently flowto the first compressor 51.

The projector 1A includes the light modulator 343 that modulates lightemitted from the light source 411. The first cooling target CT1 includesthe light source 411. The second cooling target CT2 includes the lightmodulator 343.

According to such a configuration, the light source 411 and the lightmodulator 343 can be cooled by one cooling device 5A.

The projector 1A includes the sealed housing SC as a housing in whichthe second cooling target CT2 and the second evaporator 55 are provided,and the circulation fan CF that circulates, in the sealed housing SC,the cooling gas inside the sealed housing SC. The second evaporator 55changes the working fluid in a liquid phase into the working fluid in agas phase by using heat of the cooling gas transferred from the secondcooling target CT2.

According to such a configuration, since the second cooling target CT2is provided in the sealed housing SC, dust or the like can be preventedfrom adhering to the second cooling target CT2. The second coolingtarget CT2 is cooled by the cooling gas in the sealed housing SC, andthe second evaporator 55 uses heat transferred to the cooling gas fromthe second cooling target CT2 to evaporate the working fluid in a liquidphase, so that the cooling gas inside the sealed housing SC is cooled.According to this configuration, a configuration of the cooling device5A can be simplified compared with a configuration in which the secondevaporator 55 is provided for each of the plurality of light modulators343 included in the second cooling target CT2.

Second Embodiment

Next, a second embodiment of the present disclosure will be described.

A projector according to the present embodiment has a configurationsimilar to the configuration of the projector 1A according to the firstembodiment. Here, in the cooling device 5A, the second evaporator 55includes the heat exchanger 558. In contrast, in the cooling deviceprovided in the projector according to the present embodiment, thesecond evaporator and the heat exchanger are formed separately. Theprojector according to the present embodiment is different from theprojector 1A according to the first embodiment in terms of this point.In the following description, the same or substantially the same partsas those already described are denoted by the same reference numerals,and description thereof will be omitted.

Schematic Configuration of Projector

FIG. 6 is a schematic diagram showing a configuration of a coolingdevice 5B provided in a projector 1B according to the presentembodiment.

As shown in FIG. 6, the projector 1B according to the present embodimentincludes the cooling device 5B shown in FIG. 6 instead of the coolingdevice 5A. Other configurations and functions are the same as those ofthe projector 1A according to the first embodiment.

Configuration of Cooling Device

Similarly to the cooling device 5A, the cooling device 5B cools thefirst cooling target CT1 and the second cooling target CT2.Specifically, the cooling device 5B cools the first cooling target CT1including the light source 411, and further cools the second coolingtarget CT2 including the light modulator 343 via cooling air in thesealed housing SC. The cooling device 5B has the same configuration andfunction as those of the cooling device 5A except that the coolingdevice 5B includes the second evaporator 55B instead of the secondevaporator 55, further includes a heat exchanger 60, and an arrangementof the second expander 56 is different.

Specifically, the cooling device 5B includes the first compressor 51,the condenser 52, the first expander 53, the first evaporator 54, theheat exchanger 60, the second expander 56, the second evaporator 55B,the second compressor 57, the pipe 58 that couples these units, thecooling fan 59, and a coupling pipe AT.

Similarly to the cooling device 5A, the cooling device 5B includes thefirst circulation path CR1 in which the working fluid flows through thefirst compressor 51, the first pipe 581, the condenser 52, the secondpipe 582, the first expander 53, the third pipe 583, the firstevaporator 54, and the fourth pipe 584 in this order, and the workingfluid flows into the first compressor 51 again. The first circulationpath CR1 cools the light source 411 included in the first cooling targetCT1.

Configuration of Second Circulation Path

Instead of the second circulation path CR2, the cooling device 5Bincludes a second circulation path CR3 that cools the second coolingtarget CT2. The second circulation path CR3 shares a part of the firstcirculation path CR1.

The second circulation path CR3 is a circulation path in which theworking fluid flows through the first compressor 51, the first pipe 581,the condenser 52, the second pipe 582, the first expander 53, the thirdpipe 583, the heat exchanger 60, the fifth pipe 585, the second expander56, the sixth pipe 586, the heat exchanger 60, the coupling pipe AT, thesecond evaporator 55B, the seventh pipe 587, the second compressor 57,and the fourth pipe 584 in this order, and the working fluid flows intothe first compressor 51 again.

Among these components, the first compressor 51, the first pipe 581, thecondenser 52, the second pipe 582, the first expander 53, the third pipe583, the seventh pipe 587, the second compressor 57, and the fourth pipe584 are the same as the configurations of the second circulation pathCR2.

Configuration of Heat Exchanger

As described above, the heat exchanger 60 is provided separately fromthe second evaporator 55B. The heat exchanger 60 exchanges heat betweenthe working fluid flowing from the first expander 53 and the workingfluid flowing from the second expander 56. Specifically, the heatexchanger 60 cools the working fluid that is in a state in which aliquid phase and a gas phase are mixed and that flows from the firstexpander 53 by the working fluid that is in a state in which a liquidphase and a gas phase are mixed and that flows from the second expander56, and changes the working fluid flowing from the first expander 53into a working fluid in a liquid phase. The working fluid that waschanged to a liquid phase flows to the second expander 56.

FIG. 7 is a schematic diagram showing an internal configuration of theheat exchanger 60.

As shown in FIG. 7, the heat exchanger 60 includes a first flow pathforming portion 601, a second flow path forming portion 602, and a heatinsulation portion 603.

The first flow path forming portion 601 is a tubular member for theworking fluid flowing from the first expander 53 to flow through. Thefirst flow path forming portion 601 includes a first inflow portion6011, a first flow path 6012, and a first outflow portion 6013.

The first inflow portion 6011 is coupled with the branch pipe 5833 ofthe third pipe 583.

The first flow path 6012 is a flow path for the working fluid that is inthe state in which a liquid phase and a gas phase are mixed and thatflows from the first expander 53 via the first inflow portion 6011 toflow through.

The first outflow portion 6013 is coupled with one end of the fifth pipe585 whose the other end is coupled with the second expander 56.

The second flow path forming portion 602 is a tubular member for theworking fluid flowing from the second expander 56 to flow through. Thesecond flow path forming portion 602 includes a second inflow portion6021, a second flow path 6022, and a second outflow portion 6023.

The second inflow portion 6021 is coupled with the one end of the sixthpipe 586 whose the other end is coupled with the second expander 56.

The second flow path 6022 is a flow path for the working fluid that isin the state in which a liquid phase and a gas phase are mixed and flowsfrom the second expander 56 via the second inflow portion 6021 to flowthrough.

The second outflow portion 6023 is coupled with one end of the couplingpipe AT whose the other end is coupled with the second evaporator 55B.The working fluid flowing into the second evaporator 55B from the secondoutflow portion 6023 via the coupling pipe AT is evaporated in thesecond evaporator 55B by using heat of the second cooling target CT2,and then flows to the second compressor 57 via the seventh pipe 587.That is, the working fluid flowing through the second flow path 6022 isused by the second evaporator 55B to cool the second cooling target CT2.

In this manner, the heat exchanger 60 cools the working fluid that is inthe state in which a liquid phase and a gas phase are mixed, that flowsfrom the first expander 53, and that flows through the first flow path6012 by using the working fluid that is in the state in which a liquidphase and a gas phase are mixed, that flows from the second expander 56,and that flows through the second flow path 6022.

The heat insulation portion 603 covers a periphery of the first flowpath forming portion 601 and a periphery of the second flow path formingportion 602, and realizes heat insulation between the first flow pathforming portion 601 and the second flow path forming portion 602 and anoutside of the heat exchanger 60. That is, the heat insulation portion603 covers the first flow path 6012 and the second flow path 6022. Theheat insulation portion 603 is formed of a heat insulation material.

In such a heat exchanger 60, the first flow path forming portion 601 andthe second flow path forming portion 602 are in contact with each other.That is, the first flow path 6012 and the second flow path 6022 arecoupled to each other in a heat transferable manner. Therefore, theworking fluid flowing from the first expander 53 and flowing through thefirst flow path 6012 is cooled by the working fluid that is the workingfluid expanded by the second expander 56 and that flows through thesecond flow path 6022. That is, the working fluid that is in the statein which a liquid phase and a gas phase are mixed and that is theworking fluid flowing through the first flow path 6012 is changed to theworking fluid in a liquid phase by the working fluid cooled by thesecond expander 56. Therefore, the working fluid flowing from the firstexpander 53 to the second expander 56 via the heat exchanger 60 can bechanged into the working fluid in a liquid phase. As described above,generation of abnormal noises in the second expander 56 can beprevented.

Here, in the heat exchanger 60 in FIGS. 6 and 7, a flowing direction ofthe working fluid in the first flow path 6012 and a flowing direction ofthe working fluid in the second flow path 6022 are opposite to eachother. However, the present disclosure is not limited thereto. Theflowing direction of the working fluid in the first flow path and theflowing direction of the working fluid in the second flow path may bethe same direction.

In addition, the first flow path 6012 and the second flow path 6022 arenot limited to a linearly extending flow path. For example, the firstflow path 6012 may meander from the first inflow portion 6011 toward thefirst outflow portion 6013. Similarly, the second flow path 6022 maymeander from the second inflow portion 6021 toward the second outflowportion 6023. That is, each of the first flow path 6012 and the secondflow path 6022 may have a bent portion, a folded portion, or a returnportion that changes a flowing direction of the working fluid.

Configuration of Second Evaporator

Similarly to the second evaporator 55 according to the first embodiment,the second evaporator 55B is provided in the sealed housing SC in whichthe second cooling target CT2 is provided. The second evaporator 55B iscoupled with the heat exchanger 60 via the coupling pipe AT, and iscoupled with the second compressor 57 via the seventh pipe 587.

The second evaporator 55B evaporates the working fluid in a liquid phaseflowing into the second flow path 6022 from the second expander 56 byusing heat of the cooling gas in the sealed housing SC that receivesheat from at least one heat source of the second cooling target CT2 tochange the working fluid into the working fluid in a gas phase. That is,the second evaporator 55B changes the working fluid in a liquid phaseafter flowing through the second flow path 6022 of the heat exchanger 60into the working fluid in a gas phase. The working fluid that waschanged to the working fluid in a gas phase by the second evaporator 55Bflows to the second compressor 57 via the seventh pipe 587.

Effects of Second Embodiment

The projector 1B according to the present embodiment described above canachieve the same effects as those of the projector 1A according to thefirst embodiment, and can further achieve the following effects.

For example, the projector 1B modulates and projects light emitted fromthe light source 411. The projector 1B includes the first cooling targetCT1, the second cooling target CT2, the cooling device 5B that cools thefirst cooling target CT1 and the second cooling target CT2, and theexterior housing 2 that accommodates the first cooling target CT1, thesecond cooling target CT2, and the cooling device 5B.

The cooling device 5B includes the first pipe 581, the second pipe 582,the third pipe 583, the fourth pipe 584, the fifth pipe 585, the sixthpipe 586, the seventh pipe 587, the first compressor 51, the condenser52, the first expander 53, the first evaporator 54, the heat exchanger60, the second expander 56, the second evaporator 55B, and the secondcompressor 57.

The first compressor 51 compresses the working fluid in a gas phase.

The condenser 52 is coupled with the first compressor 51 via the firstpipe 581. The condenser 52 condenses the working fluid in a gas phasecompressed by the first compressor 51 into the working fluid in a liquidphase.

The first expander 53 is coupled with the condenser 52 via the secondpipe 582. The first expander 53 decompresses the working fluid in aliquid phase condensed by the condenser 52, and changes a state of theworking fluid to a state in which a liquid phase and a gas phase aremixed.

The first evaporator 54 is coupled with the first expander 53 via thethird pipe 583. The first evaporator 54 changes a part of the workingfluid flowing from the first expander 53 to the working fluid in a gasphase by using heat transferred from the first cooling target CT1. Thefirst evaporator 54 discharges the working fluid that was changed to theworking fluid in a gas phase to the first compressor 51 coupled with thefirst evaporator 54 via the fourth pipe 584.

The heat exchanger 60 is coupled with the first expander 53 via thethird pipe 583. The heat exchanger 60 includes the first flow path 6012through an inside of which the other part of the working fluid flowingfrom the first expander 53 flows, and the second flow path 6022different from the first flow path 6012.

The second expander 56 is coupled with the heat exchanger 60 via thefifth pipe 585. The second expander 56 decompresses the working fluidflowing from the first flow path 6012 and changes a state of the workingfluid to a state in which a liquid phase and a gas phase are mixed. Thesecond expander 56 discharges the changed working fluid to the secondflow path 6022 of the heat exchanger 60 via the sixth pipe 586.

The second evaporator 55 changes the working fluid in a liquid phaseflowing into the second flow path 6022 from the second expander 56 tothe working fluid in a gas phase by using heat transferred from thesecond cooling target CT2.

The second compressor 57 is coupled with the first compressor 51 via thefourth pipe 584, and is coupled with the second evaporator 55B via theseventh pipe 587. The second compressor 57 compresses the working fluidin a gas phase flowing from the second evaporator 55B.

The heat exchanger 60 cools the working fluid flowing from the firstexpander 53 and flowing through the first flow path 6012 by the workingfluid flowing from the second expander 56 and flowing through the secondflow path 6022.

According to such a configuration, similarly to the cooling device 5A,the first cooling target CT1 can be cooled by the first circulation pathCR1. The second cooling target CT2 can be cooled by the secondcirculation path CR3 in which the working fluid flows through the firstcompressor 51, the first pipe 581, the condenser 52, the second pipe582, the first expander 53, the third pipe 583, the heat exchanger 60,the fifth pipe 585, the second expander 56, the sixth pipe 586, the heatexchanger 60, the second evaporator 55B, the seventh pipe 587, thesecond compressor 57, and the fourth pipe 584, and the working fluidflows to the first compressor 51 again.

Accordingly, the first cooling target CT1 and the second cooling targetCT2 can be cooled by one cooling device 5B. Therefore, it is notnecessary to provide a circulation path in which the working fluidcirculates for each cooling target, and the first circulation path CR1that cools the first cooling target CT1 and the second circulation pathCR3 that cools the second cooling target CT2 can share the firstcompressor 51, the first pipe 581, the condenser 52, the second pipe582, and the first expander 53. Therefore, the projector 1B can bereduced in size.

Further, the cooling device 5B is provided in the exterior housing 2together with the first cooling target CT1 and the second cooling targetCT2. According to this configuration, the projector 1B can be easilyinstalled and an appearance of the projector 1B can be improved comparedwith a case in which a part of the cooling device 5B is provided outsidethe exterior housing 2. Further, the projector 1B can be implemented ina small size, and the projector 1B can be implemented to be portable.

Due to the heat exchanger 60, the working fluid in a liquid phaseinstead of the working fluid in the state in which a liquid phase and agas phase are mixed can flow to the second expander 56. Accordingly,abnormal noises generated during expansion of the working fluid by thesecond expander 56 can be prevented. Therefore, noise reduction of thecooling device 5B and the projector 1B can be achieved.

The heat exchanger 60 includes the heat insulation portion 603 thatcovers the first flow path 6012 and the second flow path 6022.

According to such a configuration, a temperature of the working fluidflowing through the first flow path 6012 and a temperature of theworking fluid flowing through the second flow path 6022 can be preventedfrom being affected by a periphery of the heat exchanger 60 and can beprevented from increasing or reducing.

Modification of Second Embodiment

FIG. 8 is a schematic diagram showing an internal configuration of aheat exchanger 61 that is a modification of the heat exchanger 60.

The heat exchanger 60 in the cooling device 5B includes the first flowpath forming portion 601 and the second flow path forming portion 602that are tubular members, and the first flow path forming portion 601and the second flow path forming portion 602 are directly coupled toeach other. However, the present disclosure is not limited thereto.Similarly to the second evaporator 55 according to the first embodiment,the first flow path and the second flow path may be coupled in a heattransferable manner via a heat transfer portion. That is, the coolingdevice 5B may include the heat exchanger 61 shown in FIG. 8 instead ofthe heat exchanger 60.

Similarly to the heat exchanger 60, the heat exchanger 61 is coupledwith the first expander 53 and the second expander 56, cools the workingfluid flowing from the first expander 53 by the working fluid flowingfrom the second expander 56, and changes the working fluid flowing tothe second expander 56 into the working fluid in a liquid phase. Theheat exchanger 61 includes the first inflow portion 6011, the first flowpath 6012, the first outflow portion 6013, the second inflow portion6021, the second flow path 6022, the second outflow portion 6023, a heattransfer portion 611, and a heat insulation portion 612.

The heat transfer portion 611 is formed of a heat transfer material suchas metal. In the heat exchanger 61, the first inflow portion 6011, thefirst flow path 6012, the first outflow portion 6013, the second inflowportion 6021, the second flow path 6022, and the second outflow portion6023 are provided in the heat transfer portion 611. That is, the firstflow path 6012 and the second flow path 6022 are coupled to each otherin a heat transferable manner by the heat transfer portion 611.

The heat transfer portion 611 transfers heat of the working fluidflowing from the first expander 53 and flowing through the first flowpath 6012 to the working fluid flowing from the second expander 56 andflowing through the second flow path 6022, and cools the working fluidflowing through the first flow path 6012. Accordingly, the working fluidflowing through the first flow path 6012 and flowing to the secondexpander 56 is changed from the working fluid in the state in which aliquid phase and a gas phase are mixed to the working fluid in a liquidphase.

A heat insulation portion 612 covers a periphery of the heat transferportion 611. That is, similarly to the heat insulation portion 603, theheat insulation portion 612 is formed of a heat insulation material andcovers a periphery of the first flow path 6012 and a periphery of thesecond flow path 6022.

The projector 1B provided with the cooling device 5B including the heatexchanger 61 instead of the heat exchanger 60 can achieve the sameeffects as those of the projector 1B provided with the cooling device 5Bincluding the heat exchanger 60, and can further achieve the followingeffects.

For example, the heat exchanger 61 includes the first flow path 6012 andthe second flow path 6022, and includes the heat transfer portion 611that transfers heat from the working fluid flowing through the firstflow path 6012 to the working fluid flowing through the second flow path6022.

According to such a configuration, heat exchange between the workingfluid flowing through the first flow path 6012 and the working fluidflowing through the second flow path 6022 can be promoted compared witha case in which a gas such as air is present between the first flow path6012 and the second flow path 6022. Therefore, the working fluid flowingthrough the first flow path 6012 and before flowing into the secondexpander 56 can be easily changed into the working fluid in a liquidphase.

Modification of Embodiment

The present disclosure is not limited to the embodiments describedabove, and includes modifications, improvements, and the like within ascope in which the object of the present disclosure can be achieved.

According to the first embodiment, the first flow path 552 and thesecond flow path 555 provided in the second evaporator 55 are providedin the heat transfer portion 557, and heat is exchanged between theworking fluid flowing through the first flow path 552 and the workingfluid flowing through the second flow path 555 via the heat transferportion 557. However, the present disclosure is not limited thereto.Similarly to the heat exchanger 60 according to the second embodiment,the second evaporator 55 may include a tubular member constituting thefirst flow path 552 and a tubular member constituting the second flowpath 555, and the tubular members may be directly coupled to each otherin a heat transferable manner.

That is, the second evaporator 55 may be provided with the first flowpath 552 and the second flow path 555, and may not include the heattransfer portion 557 that transfers heat from the working fluid flowingthrough the first flow path 552 to the working fluid flowing through thesecond flow path 555.

According to the second embodiment, the heat exchanger 60, 61 includesthe heat insulation portion 603, 612 that covers a periphery of thefirst flow path 6012 and a periphery of the second flow path 6022.However, the present disclosure is not limited thereto. The heatexchanger 60, 61 may not include the heat insulation portion 603, 612.That is, the heat exchanger 60 according to the second embodiment maysimply have a configuration in which the first flow path 6012 and thesecond flow path 6022 are directly coupled. Heat is exchanged betweenthe first flow path 6012 and the second flow path 6022 by directlycoupling the two flow paths.

According to the first embodiment, the second evaporator 55 does notinclude a heat insulation portion. However, the present disclosure isnot limited thereto. The second evaporator 55 may include a heatinsulation portion that covers a periphery of a part of the first flowpath 552 and the second flow path 555.

In the embodiments described above, the first expander 53 and the secondexpander 56 are implemented by expansion valves. However, the presentdisclosure is not limited thereto. At least one expander of the firstexpander 53 and the second expander 56 may have a configuration otherthan the expansion valve, such as a capillary tube.

An opening degree of the expansion valve constituting the first expander53 and an opening degree of the expansion valve constituting the secondexpander 56 can be separately adjusted. However, the present disclosureis not limited thereto. Only an opening degree of an expansion valveconstituting one of the first expander 53 and the second expander 56 maybe adjustable, or an opening degree of the expansion valve constitutingeach of the expanders 53 and 56 may not be adjustable.

In the embodiments described above, a drive frequency of the firstcompressor 51 and a drive frequency of the second compressor 57 aresubstantially the same. However, the present disclosure is not limitedthereto. When noises of the first compressor 51 and noises of the secondcompressor 57 are sufficiently small, the drive frequency of the firstcompressor 51 and the drive frequency of the second compressor 57 maynot be the same.

In the embodiments described above, a flow rate of the working fluidflowing to the first evaporator 54 via the branch pipe 5832 serving asthe first branch pipe is larger than a flow rate of the working fluidflowing to the heat exchanger 558, 60, and 61 via the branch pipe 5833serving as the second branch pipe. However, the present disclosure isnot limited thereto. The flow rate of the working fluid flowing to thefirst evaporator and the flow rate of the working fluid flowing to theheat exchanger may be the same, or the flow rate of the working fluidflowing to the heat exchanger may be larger than the flow rate of theworking fluid flowing to the first evaporator.

A management temperature range of the second cooling target CT2 is lowerthan the management temperature range of the first cooling target CT1.However, the present disclosure is not limited thereto. The managementtemperature range of the second cooling target may be higher than or thesame as the management temperature range of the first cooling target.

In the embodiments described above, a pressure of the working fluid in agas phase compressed by the second compressor 57 is substantially thesame as a pressure of the working fluid in a gas phase discharged fromthe first evaporator 54. However, the present disclosure is not limitedthereto. The pressures of the working fluids in a gas phase may bedifferent. In other words, the pressure of the working fluid in a gasphase flowing into the joining pipe 5843 from the first evaporator 54via the branch pipe 5841 and the pressure of the working fluid in a gasphase flowing into the joining pipe 5843 from the second compressor 57via the branch pipe 5842 may be different. That is, between the pressureof the working fluid in a gas phase flowing to the joining pipe 5843 viathe branch pipe 5841 and the pressure of the working fluid in a gasphase flowing to the joining pipe 5843 via the branch pipe 5842, onepressure may be higher than the other pressure.

In the embodiments described above, the first cooling target CT1 cooledby the first evaporator 54 constituting the first circulation path CR1includes the light source 411, and the second cooling target CT2 cooledby the second evaporator 55, 55B constituting the second circulationpath CR2, CR3 includes the light modulator 343. However, the presentdisclosure is not limited thereto, and each cooling target may haveother configurations. For example, a cooling target of the coolingdevice 5A, 5B may be an optical component such as the polarizationconversion element 313, the polarization separation element 44, thewavelength conversion unit 461 of the wavelength conversion element 46,and a reflection plate of the diffusion reflection unit 49, or may be acircuit element provided in a control device or a power supply device.

For example, one of the first cooling target and the second coolingtarget may be one of a plurality of light sources, and the other coolingtarget may be another one of the plurality of light sources. Further,for example, one of the first cooling target and the second coolingtarget may be one of a plurality of light modulators 343, and the othercooling target may be another one of the plurality of light modulators.That is, when a plurality of cooling targets that are of the same typebut have at least one of different management temperatures, heatgeneration amounts, and cooling difficulties are provided, at least oneof the cooling targets is defined as the first cooling target and othercooling targets are defined as the second cooling target.

For example, the cooling device may include a branching portion at whichthe working fluid flowing out of the second expander 56 branches to aplurality of second evaporators 55, 55B.

In the embodiments described above, the second evaporator 55, 55B isprovided in the sealed housing SC together with the second coolingtarget CT2 including the light modulator 343, and changes the workingfluid in a liquid phase into the working fluid in a gas phase by usingheat of the cooling gas that is a gas inside the sealed housing SC andflows to the second cooling target CT2, so that the second coolingtarget CT2 is cooled. That is, the second evaporator 55, 55B cools thecooling gas by consuming heat of the cooling gas transferred from thesecond cooling target CT2, and cools the second cooling target CT2 bycirculating the cooling gas. However, the present disclosure is notlimited thereto. The second evaporator 55, 55B may not be provided inthe sealed housing SC. That is, the second evaporator 55, 55B may coolthe cooling gas flowing to the second cooling target CT2 without beingprovided in the sealed housing SC. Similarly to the first evaporator 54,the second evaporator 55, 55B may be coupled with the second coolingtarget CT2 in a heat transferable manner, and may directly cool thesecond cooling target CT2. Further, the housing in which the secondevaporator 55, 55B is provided may not be a sealed housing into which agas is less likely to enter from outside.

Further, the circulation fan CT may not be necessarily provided as longas the second cooling target CT2 can be cooled by the cooling gas insidethe sealed housing. Instead of the circulation fan CF, a fan thatcirculates the cooling gas cooled by the second evaporator 55 to thesecond cooling target CT2 may be provided.

In addition, the first evaporator 54 and the first cooling target CT1may be provided in another housing provided in the exterior housing 2,and the first evaporator 54 may cool the cooling gas flowing to thefirst cooling target CT1 in the another housing.

In addition, the cooling targets cooled by the first evaporator 54 andthe second evaporator 55, 55B may not necessarily be provided in ahousing such as the sealed housing SC.

In the embodiments described above, the cooling device 5A, 5B includesthe cooling fan 59 that circulates the cooling gas to the condenser 52.However, the present disclosure is not limited thereto. The coolingdevice 5A, 5B may not necessarily include the cooling fan 59.

In the embodiments described above, the projector 1A, 1B includes theimage projection device 3 shown in FIG. 2, and the image projectiondevice 3 includes the light source device 4 shown in FIG. 3. However,the present disclosure is not limited thereto. A configuration and alayout of optical components provided in the image projection device 3can be changed as appropriate, and a configuration and a layout ofoptical components provided in the light source device 4 can be changedas appropriate. For example, although the wavelength conversion element46 provided in the light source device 4 is a reflective wavelengthconversion element that emits the fluorescence YL generated by thewavelength conversion unit 461 to an incident side of the blue lightbeam L1 s, the light source device may use a transmissive wavelengthconversion element that emits the fluorescence along an incidentdirection of the blue light beam L1 s.

In the embodiments described above, the light source 411 of the lightsource device 4 includes the semiconductor lasers 412 and 413. However,the present disclosure is not limited thereto. The light source device 4may include, as a light source, a light source lamp such as anultra-high pressure mercury lamp or another solid light source such asan LED. The light source device 4 may include, as a light source,another solid light source or light source lamp such as an LD or an LEDthat emits a red light beam, a green light beam, and a blue light beam.In this case, a cooling target of the cooling device 5A, 5B may be thesolid light source or the light source lamp.

In the embodiments described above, the projector 1A, 1B includes threelight modulators 343 (343B, 343G, and 343R). However, the presentdisclosure is not limited thereto. The present disclosure can also beapplied to a projector including two or less or four or more lightmodulators.

In the embodiments described above, the light modulator 343 is atransmissive liquid crystal panel whose light incident surface and lightemitting surface are different. However, the present disclosure is notlimited thereto. The reflective liquid crystal panel whose lightincident surface and light exit surface are the same may be used as thelight modulator. As long as the light modulator can modulate an incidentlight beam and form an image according to image information, the lightmodulator may use a device other than a liquid crystal panel, such as adevice using a micromirror or a device using a digital micromirrordevice (DMD) or the like.

Overview of Present Disclosure

The present disclosure will be overviewed as follows.

A projector according to an aspect of the present disclosure modulatesand projects light emitted from a light source. The projector includes afirst cooling target, a second cooling target, a cooling device thatcools the first cooling target and the second cooling target, and anexterior housing that accommodates the first cooling target, the secondcooling target, and the cooling device. The cooling device includes afirst pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, asixth pipe, a seventh pipe, a first compressor that compresses a workingfluid in a gas phase, a condenser that is coupled with the firstcompressor via the first pipe, and that condenses the working fluid in agas phase compressed by the first compressor into a working fluid in aliquid phase, a first expander that is coupled with the condenser viathe second pipe, and that decompresses the working fluid in a liquidphase condensed by the condenser to change the working fluid in a liquidphase into a working fluid in a mixed phase of a liquid phase and a gasphase, a first evaporator that is coupled with the first expander viathe third pipe, that changes a part of the working fluid flowing fromthe first expander into the working fluid in a gas phase by using heattransferred from the first cooling target, and that discharges theworking fluid changed into a gas phase to the first compressor coupledwith the first evaporator via the fourth pipe, a heat exchanger that iscoupled with the first expander via the third pipe, and that includes afirst flow path through an inside of which the other part of the workingfluid flowing from the first expander flows and a second flow pathdifferent from the first flow path, a second expander that is coupledwith the heat exchanger via the fifth pipe, that decompresses theworking fluid in a liquid phase flowing from the first flow path tochange the working fluid in a liquid phase into the working fluid in amixed phase of a liquid phase and a gas phase, and that discharges theworking fluid in a mixed phase of a liquid phase and a gas phase to thesecond flow path of the heat exchanger via the sixth pipe, a secondevaporator that changes the working fluid in a liquid phase flowing intothe second flow path from the second expander into the working fluid ina gas phase by using heat transferred from the second cooling target,and a second compressor that is coupled with the first compressor viathe fourth pipe, that is coupled with the second evaporator via theseventh pipe, and that compresses the working fluid in a gas phaseflowing from the second evaporator. The heat exchanger cools the workingfluid flowing from the first expander and flowing through the first flowpath by the working fluid flowing from the second expander and flowingthrough the second flow path.

According to such a configuration, the first cooling target can becooled by a first circulation path in which the working fluid flowsthrough the first compressor, the first pipe, the condenser, the secondpipe, the first expander, the third pipe, the first evaporator, and thefourth pipe, and the working fluid flows to the first compressor again.The second cooling target can be cooled by a second circulation path inwhich the working fluid flows through the first compressor, the firstpipe, the condenser, the second pipe, the first expander, the thirdpipe, the heat exchanger, the fifth pipe, the second expander, the sixthpipe, the heat exchanger, the second evaporator, the seventh pipe, thesecond compressor, and the fourth pipe, and the working fluid flows tothe first compressor again.

Accordingly, the first cooling target and the second cooling target canbe cooled by one cooling device. Therefore, it is not necessary toprovide a circulation path in which the working fluid circulates foreach cooling target, and the first circulation path that cools the firstcooling target and the second circulation path that cools the secondcooling target can share the first compressor, the first pipe, thecondenser, the second pipe, and the first expander. Therefore, theprojector including the cooling device can be reduced in size.

Further, the cooling device is provided in the exterior housing togetherwith the first cooling target and the second cooling target. Accordingto this configuration, the projector can be easily installed and anappearance of the projector can be improved compared with a case inwhich a part of the cooling device is provided outside the exteriorhousing. Further, the projector can be implemented in a small size, andthe projector can be implemented to be portable.

Here, in a case in which the working fluid flowing to the secondexpander is the working fluid in a state in which a liquid phase and agas phase are mixed, abnormal noises are generated when the secondexpander implemented by an electronic expansion valve expands theworking fluid.

In contrast, in the heat exchanger, the working fluid flowing throughthe first flow path and before flowing into the second expander iscooled by the working fluid flowing from the second expander and flowingthrough the second flow path, and the working fluid flowing through thefirst flow path and before flowing into the second expander is changedinto the working fluid in a liquid phase. Accordingly, the working fluidin a liquid phase instead of the working fluid in the state in which aliquid phase and a gas phase are mixed can flow to the second expander.Accordingly, abnormal noises generated during expansion of the workingfluid by the second expander can be prevented. Therefore, noisereduction of the cooling device and the projector can be achieved.

In the above aspect, the heat exchanger may be provided in the secondevaporator.

According to such a configuration, it is not necessary to separatelyprovide the second evaporator and the heat exchanger. Therefore, aconfiguration of the cooling device can be prevented from becomingcomplicated since an increase in the number of components of the coolingdevice can be prevented. In addition, manufacturing costs of the coolingdevice and the projector can be prevented from increasing.

In the above aspect, the first flow path and the second flow path may becoupled to each other in a heat transferable manner.

According to such a configuration, the working fluid flowing through thefirst flow path can be cooled by the working fluid flowing through thesecond flow path. Therefore, the working fluid flowing through the firstflow path and flowing to the second expander can be easily changed intothe working fluid in a liquid phase.

In the above aspect, the heat exchanger may include a heat transferportion that is provided with the first flow path and the second flowpath and transfers heat from the working fluid flowing through the firstflow path to the working fluid flowing through the second flow path.

According to such a configuration, heat exchange between the workingfluid flowing through the first flow path and the working fluid flowingthrough the second flow path can be promoted compared with a case inwhich a gas such as air is present between the first flow path and thesecond flow path. Therefore, the working fluid flowing through the firstflow path and before flowing into the second expander can be easilychanged into the working fluid in a liquid phase.

In the above aspect, the heat exchanger may include a heat insulationportion that covers the first flow path and the second flow path.

According to such a configuration, a temperature of the working fluidflowing through the first flow path and a temperature of the workingfluid flowing through the second flow path can be prevented from beingaffected by a periphery of the heat exchanger and can be prevented fromincreasing or reducing.

In the above aspect, each of the first expander and the second expandermay be implemented by an expansion valve, and an opening degree of theexpansion valve constituting the first expander and an opening degree ofthe expansion valve constituting the second expander may be separatelyadjustable.

According to such a configuration, a temperature of the working fluidflowing out of the first expander and a temperature of the working fluidflowing out of the second expander can be separately adjusted.Therefore, the temperature of the working fluid flowing out of the firstexpander can be set to a temperature suitable for cooling the firstcooling target, and the temperature of the working fluid flowing out ofthe second expander can be set to a temperature suitable for cooling thesecond cooling target.

In the above aspect, a drive frequency of the first compressor and adrive frequency of the second compressor may be substantially the same.

Here, when the drive frequency of the first compressor and the drivefrequency of the second compressor are different, noises of the firstcompressor and noises of the second compressor overlap with each otherat timing when phases of the drive frequencies coincide with each other,noises of the cooling device increase. In this case, the noises increaseat a constant cycle, and the user is likely to feel discomfort. When adifference between the drive frequency of the first compressor and thedrive frequency of the second compressor is very large, a cycle in whichphases coincide with each other is very long and a discomfort feeling ofthe user is not much. However, when the difference between the drivefrequency of the first compressor and the drive frequency of the secondcompressor is very large, that is, when the drive frequency of the firstcompressor is greatly different from the drive frequency of the secondcompressor, the second compressor cannot compress the working fluidflowing from the second evaporator in accordance with a pressure of theworking fluid flowing from the first evaporator to the first compressor.

In contrast, since the drive frequency of the first compressor and thedrive frequency of the second compressor are substantially the same,noises can be prevented from becoming large at a constant cycle whilecompression performance of the compressors can be ensured. Therefore,the user is less likely to feel discomfort.

In the above aspect, the third pipe may include a flow dividing pipe atwhich the working fluid flowing from the first expander branches, afirst branch pipe in which a part of the working fluid branching at theflow dividing pipe flows to the first evaporator, and a second branchpipe in which the other part of the working fluid branching at the flowdividing pipe flows to the heat exchanger, and the fourth pipe mayinclude a third branch pipe coupled with the first evaporator, a fourthbranch pipe coupled with the second compressor, and a joining pipe inwhich the working fluid flowing from the first evaporator via the thirdbranch pipe and the working fluid flowing from the second compressor viathe fourth branch pipe join each other and flow to the first compressor.

According to such a configuration, the working fluid can flow from thefirst expander to the first evaporator and the heat exchanger. Theworking fluid can flow from the first evaporator and the secondcompressor to the first compressor.

In the above aspect, a heat generation amount of the first coolingtarget is larger than a heat generation amount of the second coolingtarget, and a flow rate of the working fluid supplied to the firstevaporator may be larger than a flow rate of the working fluid suppliedto the heat exchanger.

According to such a configuration, more working fluid in a liquid phasecan flow to the first evaporator that cools the first cooling targethaving a larger heat generation amount than the heat generation amountof the second cooling target cooled by the second evaporator. Therefore,the working fluid at a flow rate suitable for cooling the first coolingtarget can flow to the first evaporator, and a temperature of the firstcooling target can be easily maintained at a management temperature.

In the above aspect, a management temperature range of the secondcooling target may be lower than a management temperature range of thefirst cooling target.

According to such a configuration, the working fluid flowing to thesecond evaporator flows from the condenser to the first expander, theheat exchanger, and the second expander. Therefore, a temperature of theworking fluid flowing to the second evaporator that cools the secondcooling target can be lower than a temperature of the working fluidflowing to the first evaporator that cools the first cooling target.Accordingly, working fluids having suitable temperatures for cooling thefirst cooling target and the second cooling target having a managementtemperature range lower than the management temperature range of thefirst cooling target can respectively flow in the first evaporator andthe second evaporator. Therefore, the cooling of the first coolingtarget and the cooling of the second cooling target can be suitablyperformed.

In the above aspect, a pressure of the working fluid in a gas phasecompressed by the second compressor may be substantially the same as apressure of the working fluid in a gas phase discharged from the firstevaporator.

According to such a configuration, the working fluid in a gas phasedischarged from the first evaporator and the working fluid in a gasphase compressed by the second compressor can easily join each other inthe fourth pipe. Therefore, the working fluid in a gas phase dischargedfrom the first evaporator and the working fluid in a gas phasedischarged from the second compressor can easily and efficiently flow tothe first compressor.

In the above aspect, the projector may include a light modulator thatmodulates light emitted from the light source, the first cooling targetmay include the light source, and the second cooling target may includethe light modulator.

According to such a configuration, the light source and the lightmodulator can be cooled by one cooling device.

In the above aspect, the projector may include a housing in which thesecond cooling target and the second evaporation portion are provided,and a circulation fan that circulates, in the housing, a cooling gasinside the housing, and the second evaporator may change the workingfluid in a liquid phase into the working fluid in a gas phase by usingheat of the cooling gas transferred from the second cooling target.

According to such a configuration, since the second cooling target isprovided in the housing, dust or the like can be prevented from adheringto the second cooling target. The second cooling target is cooled by thecooling gas in the housing, and the second evaporator uses heattransferred to the cooling gas from the second cooling target toevaporate the working fluid in a liquid phase, so that the cooling gasinside the housing is cooled. According to this configuration, aconfiguration of the cooling device can be simplified compared with acase in which the second evaporator is provided for each second coolingtarget when there are a plurality of second cooling targets.

What is claimed is:
 1. A projector that modulates and projects lightemitted from a light source, the projector comprising: a first coolingtarget; a second cooling target; a cooling device configured to cool thefirst cooling target and the second cooling target; and an exteriorhousing accommodating the first cooling target, the second coolingtarget, and the cooling device, wherein the cooling device includes: afirst pipe, a second pipe, a third pipe, a fourth pipe, a fifth pipe, asixth pipe, a seventh pipe, a first compressor configured to compress aworking fluid in a gas phase, a condenser coupled with the firstcompressor via the first pipe, and configured to condense the workingfluid in a gas phase compressed by the first compressor into a workingfluid in a liquid phase, a first expander coupled with the condenser viathe second pipe, and configured to decompress the working fluid in aliquid phase condensed by the condenser to change the working fluid in aliquid phase into a working fluid in a mixed phase of a liquid phase anda gas phase, a first evaporator coupled with the first expander via thethird pipe, configured to change a part of the working fluid flowingfrom the first expander into the working fluid in a gas phase by usingheat transferred from the first cooling target, and configured todischarge the working fluid changed into a gas phase to the firstcompressor coupled with the first evaporator via the fourth pipe, a heatexchanger coupled with the first expander via the third pipe, andincluding a first flow path through which the other part of the workingfluid flowing from the first expander flows and a second flow pathdifferent from the first flow path, a second expander coupled with theheat exchanger via the fifth pipe, configured to decompress the workingfluid in a liquid phase flowing from the first flow path to change theworking fluid in a liquid phase into the working fluid in a mixed phaseof a liquid phase and a gas phase, and configured to discharge theworking fluid in a mixed phase of a liquid phase and a gas phase to thesecond flow path of the heat exchanger via the sixth pipe, a secondevaporator configured to change, into the working fluid in a gas phase,the working fluid in a liquid phase flowing into the second flow pathfrom the second expander by using heat transferred from the secondcooling target, and a second compressor coupled with the firstcompressor via the fourth pipe and coupled with the second evaporatorvia the seventh pipe, the second compressor being configured to compressthe working fluid in a gas phase flowing from the second evaporator, andthe heat exchanger is configured to cool the working fluid flowing fromthe first expander into the first flow path by the working fluid flowingfrom the second expander into the second flow path.
 2. The projectoraccording to claim 1, wherein the heat exchanger is provided in thesecond evaporator.
 3. The projector according to claim 1, wherein thefirst flow path and the second flow path are coupled to each other in aheat transferable manner.
 4. The projector according to claim 3, whereinthe heat exchanger includes a heat transfer portion provided with thefirst flow path and the second flow path and configured to transfer heatfrom the working fluid flowing through the first flow path to theworking fluid flowing through the second flow path.
 5. The projectoraccording to claim 1, wherein the heat exchanger includes a heatinsulation portion covering the first flow path and the second flowpath.
 6. The projector according to claim 1, wherein the first expanderis implemented by a first expansion valve and the second expander isimplemented by a second expansion valve, and an opening degree of thefirst expansion valve and an opening degree of the second expansionvalve are separately adjustable.
 7. The projector according to claim 1,wherein a drive frequency of the first compressor and a drive frequencyof the second compressor are substantially the same.
 8. The projectoraccording to claim 1, wherein the third pipe includes: a flow dividingpipe at which the working fluid flowing from the first expanderbranches, a first branch pipe in which a part of the working fluidbranching at the flow dividing pipe flows to the first evaporator, and asecond branch pipe in which the other part of the working fluidbranching at the flow dividing pipe flows to the heat exchanger, and thefourth pipe includes: a third branch pipe coupled with the firstevaporator, a fourth branch pipe coupled with the second compressor, anda joining pipe in which the working fluid flowing from the firstevaporator via the third branch pipe and the working fluid flowing fromthe second compressor via the fourth branch pipe join each other andflow to the first compressor.
 9. The projector according to claim 1,wherein a heat generation amount of the first cooling target is largerthan a heat generation amount of the second cooling target, and a flowrate of the working fluid supplied to the first evaporator is largerthan a flow rate of the working fluid supplied to the heat exchanger.10. The projector according to claim 1, wherein a management temperaturerange of the second cooling target is lower than a managementtemperature range of the first cooling target.
 11. The projectoraccording to claim 1, wherein a pressure of the working fluid in a gasphase compressed by the second compressor is substantially the same as apressure of the working fluid in a gas phase discharged from the firstevaporator.
 12. The projector according to claim 1, further comprising:a light modulator configured to modulate light emitted from the lightsource, wherein the first cooling target includes the light source, andthe second cooling target includes the light modulator.
 13. Theprojector according to claim 1, further comprising: a housingaccommodating the second cooling target and the second evaporator, and acirculation fan configured to circulate, in the housing, a cooling gasinside the housing, wherein the second evaporator is configured tochange the working fluid in a liquid phase into the working fluid in agas phase by using heat of the cooling gas transferred from the secondcooling target.